1. Field of the Invention
The invention relates to benders for bending pipe, conduit, tubing, and the like at the point of installation. More particularly, the invention relates to a conduit bender having a pair of vertically spaced overlapping conduit-receiving grooves formed in the rocker or base portion thereof, enabling the four types of electrical conduit presently being used in the industry to be bent with the single bender of the invention.
2. Description of the Prior Art
There are numerous types and styles of portable conduit benders which are used by electricians for bending conduit at a job site to form radii of predetermined angles therein prior to installation of the conduit in a new or existing building, primarily for use as a duct for housing electrical wiring. One of the most common types of conduit benders used by electricians today has an arcuate-shaped base or rocker portion with a longitudinally extending conduit-receiving groove formed therein, with a conduit-engaging hook portion formed at one end and a foot treadle portion at the opposite end. An intervening handle is attached to the bender for applying the bending pressure to a section of conduit in combination with pressure applied to the treadle portion. Examples of these types of benders are shown in U.S. Pat. Nos. 2,584,537, 2,817,986 and 2,906,149. These benders provide a satisfactory and efficient device for bending conduit and the like on a job site and are used extensively in the building industry.
There are presently in use today four types of conduits used for duct work in electrical installations to provide a protective housing for the electrical wires. These types are referred to as EMT (electrical metallic tubing) which is a thin-wall tubing or conduit; IMC-Type 1 (intermediate metallic conduit); IMC-Type 2; and Rigid. These four types of tubing come in the various nominal size ratings, such as 1/2", 3/4", 1", and 11/4".
A different bender is required for bending the EMT thin-wall conduit for each nominal size rating than the bender which is required for the other three types of conduit for the same nominal size conduit. For example, the 1/2" EMT conduit has a 0.706" O.D., requiring a particular size bender, and the 1/2" IMC-Type 2 and 1/2" Rigid conduits have O.D.'s of 0.840", and the 1/2" IMC-Type 1 has an O.D. of 0.816". These latter three types of 1/2" conduit all can be bent with a single bender which is a different bender than the bender required for the 1/2" EMT conduit. Throughout the specification the EMT conduit will be referred to as "thin wall" and the other three types are referred to as "heavy-wall" conduits.
Therefore, an electrician is required to have two conduit benders for each nominal size conduit, increasing the cost of his tools and the additional labor required for transporting the tools to and from a job site, etc.
Accordingly, the need has existed for a single conduit bender which will satisfactorily bend the four general types of conduit in each nominal size rating, eliminating a separate bender for the thin-wall and for heavy-wall conduits. No known bender construction of which I am aware accomplishes these results.